tools/testing/selftests/vm/hugetlbfstest.c

   1 #define _GNU_SOURCE
   2 #include <assert.h>
   3 #include <fcntl.h>
   4 #include <stdio.h>
   5 #include <stdlib.h>
   6 #include <string.h>
   7 #include <sys/mman.h>
   8 #include <sys/stat.h>
   9 #include <sys/types.h>
  10 #include <unistd.h>
  11
  12 typedef unsigned long long u64;
  13
  14 static size_t length = 1 << 24;
  15
  16 static u64 read_rss(void)
  17 {
  18         char buf[4096], *s = buf;
  19         int i, fd;
  20         u64 rss;
  21
  22         fd = open("/proc/self/statm", O_RDONLY);
  23         assert(fd > 2);
  24         memset(buf, 0, sizeof(buf));
  25         read(fd, buf, sizeof(buf) - 1);
  26         for (i = 0; i < 1; i++)
  27                 s = strchr(s, ' ') + 1;
  28         rss = strtoull(s, NULL, 10);
  29         return rss << 12; /* assumes 4k pagesize */
  30 }
  31
  32 static void do_mmap(int fd, int extra_flags, int unmap)
  33 {
  34         int *p;
  35         int flags = MAP_PRIVATE | MAP_POPULATE | extra_flags;
  36         u64 before, after;
  37
  38         before = read_rss();
  39         p = mmap(NULL, length, PROT_READ | PROT_WRITE, flags, fd, 0);
  40         assert(p != MAP_FAILED ||
  41                         !"mmap returned an unexpected error");
  42         after = read_rss();
  43         assert(llabs(after - before - length) < 0x40000 ||
  44                         !"rss didn't grow as expected");
  45         if (!unmap)
  46                 return;
  47         munmap(p, length);
  48         after = read_rss();
  49         assert(llabs(after - before) < 0x40000 ||
  50                         !"rss didn't shrink as expected");
  51 }
  52
  53 static int open_file(const char *path)
  54 {
  55         int fd, err;
  56
  57         unlink(path);
  58         fd = open(path, O_CREAT | O_RDWR | O_TRUNC | O_EXCL
  59                         | O_LARGEFILE | O_CLOEXEC, 0600);
  60         assert(fd > 2);
  61         unlink(path);
  62         err = ftruncate(fd, length);
  63         assert(!err);
  64         return fd;
  65 }
  66
  67 int main(void)
  68 {
  69         int hugefd, fd;
  70
  71         fd = open_file("/dev/shm/hugetlbhog");
  72         hugefd = open_file("/hugepages/hugetlbhog");
  73
  74         system("echo 100 > /proc/sys/vm/nr_hugepages");
  75         do_mmap(-1, MAP_ANONYMOUS, 1);
  76         do_mmap(fd, 0, 1);
  77         do_mmap(-1, MAP_ANONYMOUS | MAP_HUGETLB, 1);
  78         do_mmap(hugefd, 0, 1);
  79         do_mmap(hugefd, MAP_HUGETLB, 1);
  80         /* Leak the last one to test do_exit() */
  81         do_mmap(-1, MAP_ANONYMOUS | MAP_HUGETLB, 0);
  82         printf("oll korrekt.\n");
  83         return 0;
  84 }